With a mobile terminal which is adapted to receive a message transmitted by radio through the telephone network and to store the message in the nonvolatile member and to show the message on a display, when energized, checksum for the message stored in the nonvolatile memory is calculated to store the result in a RAM. When a message is thereafter received, checksum for the received message is compared with a plurality of checksums stored in the RAM, respectively. The subject to be compared is the only stored message having the same checksum as that for the received message, and the messages are compared. When the messages are same, the received message is stored in the nonvolatile memory by overwrite. As a result, a check for a message duplicate can be performed within a shorter period of time.